1. Field of the Invention
The present invention relates to a camera in which a film-use status can be indicated by actuating an indicating mechanism provided for a film cartridge.
2. Description of the Related Art
A film cartridge provided with an indicating mechanism for indicating the film-use status of a roll of film accommodated in the cartridge has been proposed. Such an indicating mechanism indicates whether the film is totally unused, i.e. no frames are exposed at all (hereinafter referred to as "unused film"), or the film is removed while not all the frames are exposed, i.e., one or more frames are exposed and the film is then removed without exposing the rest of the frames (hereinafter referred to as "partially-used film"), or the film is completely used, i.e., all the frames are exposed (hereinafter referred to as "completely-used film"). The partially-used film can be loaded again in the camera, thereby enabling the exposure on the unexposed frames.
A camera for photographing by employing the cartridge provided with the above indicating mechanism is disclosed in U.S. patent application Ser. No. 07/728,208 (filed on Jul. 10, 1991) and U.S. patent application Ser. No. 08/112,479 (filed on Aug. 27, 1993) by the present inventor. Such a camera recognizes the actual film-use status and actuates, according to the results of the recognization, the indicating mechanism of the cartridge so as to indicate the suitable film-use status. Hence, a camera user can confirm the film-use status simply by observing the indicating mechanism of the cartridge removed from the camera. As a result, it is possible to prevent inconveniences, for example, a cartridge accommodating a completely-used film is mistakingly loaded again in the camera, or a partially-used film is mistakingly developed.
In general, when a film cartridge is loaded in the camera, film ISO sensitivity is read from a DX code provided for the cartridge and the resultant ISO sensitivity is automatically set as a parameter for calculating an exposure value. In some cases, however, the set ISO sensitivity is intentionally changed. That is, the sensitivity different from the actual film sensitivity is set and photography is then performed sometimes. In such a case, since the exposure value for photography is calculated on the basis of the changed sensitivity, a typical developing treatment cannot obtain appropriately-exposed pictures. However, if an adjustment is made to the exposure for developing according to the change in the ISO sensitivity, appropriately-exposed pictures can be obtained. Nevertheless, a mixture of frames exposed under the different setting of the sensitivity in one roll of film gets behind in the developing operation, and consequently, once the ISO sensitivity is changed when an unused film is loaded in the camera, it is necessary to perform photography while conforming to the set ISO sensitivity throughout.
However, when a film in which a few frames are exposed after changing the ISO sensitivity is removed and loaded again in the camera, frames exposed under the different setting of the sensitivity might be mixed in one roll of film if a photographer forgets that he/she has changed the sensitivity or another photographer who is not aware of the change of the sensitivity uses the film.